﻿using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace TaskMessage.DataAccess
{
    /// <summary>
    /// The SqlHelper class is intended to encapsulate high performance, scalable best practices for 
    /// common uses of SqlClient.
    /// </summary>
    public sealed class SqlHelper
    {
        //*********************************************************************
        //
        // Since this class provides only static methods, make the default constructor private to prevent 
        // instances from being created with "new SqlHelper()".
        //
        //*********************************************************************

        private SqlHelper() { }

        public static SqlDataReader ExecuteReader(SqlConnection conn, CommandType commandType, string comText, SqlParameter[] commandParameters)
        {
            try
            {
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandType = commandType;
                cmd.CommandText = comText;
                if (commandParameters != null)
                    AttachParameters(cmd, commandParameters);
                SqlDataReader reader = cmd.ExecuteReader();
                cmd.Dispose();
                return reader;
            }
            catch (Exception ex)
            {
                if (conn.State == ConnectionState.Open)
                    conn.Close();
                throw ex;
            }
        }

        //*********************************************************************
        //
        // This method is used to attach array of SqlParameters to a SqlCommand.
        // 
        // This method will assign a value of DbNull to any parameter with a direction of
        // InputOutput and a value of null.  
        // 
        // This behavior will prevent default values from being used, but
        // this will be the less common case than an intended pure output parameter (derived as InputOutput)
        // where the user provided no input value.
        // 
        // param name="command" The command to which the parameters will be added
        // param name="commandParameters" an array of SqlParameters tho be added to command
        //
        //*********************************************************************

        private static void AttachParameters(SqlCommand command, SqlParameter[] commandParameters)
        {
            foreach (SqlParameter p in commandParameters)
            {
                //check for derived output value with no value assigned
                if ((p.Direction == ParameterDirection.InputOutput) && (p.Value == null))
                {
                    p.Value = DBNull.Value;
                }

                command.Parameters.Add(p);
            }
        }

        //*********************************************************************
        //
        // This method assigns an array of values to an array of SqlParameters.
        // 
        // param name="commandParameters" array of SqlParameters to be assigned values
        // param name="parameterValues" array of objects holding the values to be assigned
        //
        //*********************************************************************

        private static void AssignParameterValues(SqlParameter[] commandParameters, object[] parameterValues)
        {
            if ((commandParameters == null) || (parameterValues == null))
            {
                //do nothing if we get no data
                return;
            }

            // we must have the same number of values as we pave parameters to put them in
            if (commandParameters.Length != parameterValues.Length)
            {
                throw new ArgumentException("Parameter count does not match Parameter Value count.");
            }

            //iterate through the SqlParameters, assigning the values from the corresponding position in the 
            //value array
            for (int i = 0, j = commandParameters.Length; i < j; i++)
            {
                commandParameters[i].Value = parameterValues[i];
            }
        }

        //*********************************************************************
        //
        // This method opens (if necessary) and assigns a connection, transaction, command type and parameters 
        // to the provided command.
        // 
        // param name="command" the SqlCommand to be prepared
        // param name="connection" a valid SqlConnection, on which to execute this command
        // param name="transaction" a valid SqlTransaction, or 'null'
        // param name="commandType" the CommandType (stored procedure, text, etc.)
        // param name="commandText" the stored procedure name or T-SQL command
        // param name="commandParameters" an array of SqlParameters to be associated with the command or 'null' if no parameters are required
        //
        //*********************************************************************

        private static void PrepareCommand(SqlCommand command, SqlConnection connection, SqlTransaction transaction, CommandType commandType, string commandText, SqlParameter[] commandParameters)
        {
            //if the provided connection is not open, we will open it
            if (connection.State != ConnectionState.Open)
            {
                connection.Open();
            }

            //associate the connection with the command
            command.Connection = connection;

            //set the command text (stored procedure name or SQL statement)
            command.CommandText = commandText;

            //if we were provided a transaction, assign it.
            if (transaction != null)
            {
                command.Transaction = transaction;
            }

            //set the command type
            command.CommandType = commandType;

            //attach the command parameters if they are provided
            if (commandParameters != null)
            {
                AttachParameters(command, commandParameters);
            }

            return;
        }

        /// <summary>
        /// Execute a SqlCommand (that returns no resultset) against the database specified in the connection string 
        /// using the provided parameters.
        /// </summary>
        /// <example>
        /// <code>
        /// int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </code>
        /// </example>
        /// <param name="connectionString">a valid connection string for a SqlConnection</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or T-SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            //create & open a SqlConnection, and dispose of it after we are done.
            using (SqlConnection cn = new SqlConnection(connectionString))
            {
                cn.Open();

                //call the overload that takes a connection in place of the connection string
                return ExecuteNonQuery(cn, commandType, commandText, commandParameters);
            }
        }

        /// <summary>
        /// Execute a SqlCommand (that returns no resultset) against the specified SqlConnection 
        /// using the provided parameters.
        /// </summary>
        /// <example>
        /// <code>
        /// int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </code>
        /// </example>
        /// <param name="connection">a valid SqlConnection </param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.) </param>
        /// <param name="commandText">the stored procedure name or T-SQL command </param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(SqlConnection connection, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            return ExecuteNonQuery(connection, null, commandType, commandText, commandParameters);
        }

        /// <summary>
        /// Execute a SqlCommand (that returns no resultset) against the specified SqlConnection 
        /// using the provided parameters.
        /// </summary>
        /// <param name="connection">a valid SqlConnection </param>
        /// <param name="transcation">transaction</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.) </param>
        /// <param name="commandText">the stored procedure name or T-SQL command </param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(SqlConnection connection, SqlTransaction transcation, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            //create a command and prepare it for execution
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, connection, transcation, commandType, commandText, commandParameters);

            //finally, execute the command.
            int retval = cmd.ExecuteNonQuery();

            // detach the SqlParameters from the command object, so they can be used again.
            cmd.Parameters.Clear();
            return retval;
        }

        /// <summary>
        /// Execute a SqlCommand (that returns a resultset) against the database specified in the connection string 
        /// using the provided parameters.
        /// </summary>
        /// <example>
        /// <code>
        /// DataSet ds = ExecuteDataset(connString, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));
        /// </code>
        /// </example>
        /// <param name="connectionString">a valid connection string for a SqlConnection</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or T-SQL command </param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>a dataset containing the resultset generated by the command</returns>
        public static DataSet ExecuteDataset(string connectionString, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            //create & open a SqlConnection, and dispose of it after we are done.
            using (SqlConnection cn = new SqlConnection(connectionString))
            {
                cn.Open();

                //call the overload that takes a connection in place of the connection string
                return ExecuteDataset(cn, commandType, commandText, commandParameters);
            }
        }

        /// <summary>
        /// Execute a SqlCommand (that returns a resultset) against the specified SqlConnection 
        /// using the provided parameters.
        /// </summary>
        /// <param name="connection">a valid SqlConnection</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or T-SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>a dataset containing the resultset generated by the command</returns>
        public static DataSet ExecuteDataset(SqlConnection connection, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            return ExecuteDataset(connection, null, commandType, commandText, commandParameters);
        }

        /// <summary>
        /// Execute a SqlCommand (that returns a resultset) against the specified SqlConnection 
        /// using the provided parameters.
        /// </summary>
        /// <param name="connection">a valid SqlConnection</param>
        /// <param name="trans">transaction</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or T-SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>a dataset containing the resultset generated by the command</returns>
        public static DataSet ExecuteDataset(SqlConnection connection, SqlTransaction trans, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            //create a command and prepare it for execution
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, connection, trans, commandType, commandText, commandParameters);

            //create the DataAdapter & DataSet
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();

            //fill the DataSet using default values for DataTable names, etc.
            da.Fill(ds);

            // detach the SqlParameters from the command object, so they can be used again.			
            cmd.Parameters.Clear();

            //return the dataset
            return ds;
        }

        /// <summary>
        /// Execute a SqlCommand (that returns a 1x1 resultset) against the database specified in the connection string 
        /// using the provided parameters.
        /// </summary>
        /// <param name="connectionString">a valid connection string for a SqlConnection </param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.) </param>
        /// <param name="commandText">the stored procedure name or T-SQL command </param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command </param>
        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
        public static object ExecuteScalar(string connectionString, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            //create & open a SqlConnection, and dispose of it after we are done.
            using (SqlConnection cn = new SqlConnection(connectionString))
            {
                cn.Open();

                //call the overload that takes a connection in place of the connection string
                return ExecuteScalar(cn, commandType, commandText, commandParameters);
            }
        }

        /// <summary>
        /// Execute a SqlCommand (that returns a 1x1 resultset) against the specified SqlConnection 
        /// using the provided parameters.
        /// </summary>
        /// <param name="connection">a valid SqlConnection </param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.) </param>
        /// <param name="commandText"> the stored procedure name or T-SQL command </param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command </param>
        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
        public static object ExecuteScalar(SqlConnection connection, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            //create a command and prepare it for execution
            return ExecuteScalar(connection, null, commandType, commandText, commandParameters);

        }

        /// <summary>
        /// Execute a SqlCommand (that returns a 1x1 resultset) against the specified SqlConnection 
        /// using the provided parameters.
        /// </summary>
        /// <param name="connection">a valid SqlConnection </param>
        /// <param name="trans">transaction</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.) </param>
        /// <param name="commandText"> the stored procedure name or T-SQL command </param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command </param>
        /// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
        public static object ExecuteScalar(SqlConnection connection, SqlTransaction trans, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            //create a command and prepare it for execution
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, connection, trans, commandType, commandText, commandParameters);

            //execute the command & return the results
            object retval = cmd.ExecuteScalar();

            // detach the SqlParameters from the command object, so they can be used again.
            cmd.Parameters.Clear();
            return retval;

        }
    }
}
